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          <th colspan="3" align="center">DbChannel::send_request()</th>
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          <td width="20%" align="left"><a accesskey="p" href="dbchannel_send_msg.html">Prev</a> </td>
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            <h2 class="title" style="clear: both"><a id="dbchannel_send_request"></a>DbChannel::send_request()</h2>
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      <pre class="programlisting">#include &lt;db_cxx.h&gt;

int 
DbChannel::send_request(Dbt *request, u_int32_t nrequest, 
                        Dbt *response, db_timeout_t timeout,
                        u_int32_t flags);</pre>
      <p>
        The <code class="methodname">DbChannel::send_request()</code> method
        sends a message on the message channel. The message is sent
        synchronously; the method blocks waiting for a response before
        returning.  If a response is not received within the timeout value
        configured for this request, this method returns with an error
        condition.
    </p>
      <p>
        If you do not want to block while waiting for a response from a remote
        site, use the 
        <a class="xref" href="dbchannel_send_msg.html" title="DbChannel::send_msg()">DbChannel::send_msg()</a> 
        method.
    </p>
      <p>
        The message sent by this method is received and handled at 
        remote sites using a message dispatch callback, which is configured
        using the <a class="xref" href="repmgr_msg_dispatch.html" title="DbEnv::repmgr_msg_dispatch()">DbEnv::repmgr_msg_dispatch()</a>
        method. 
    </p>
      <p>
         The <code class="methodname">DbChannel::send_request()</code> <span>
            
            <span>
                method either returns a non-zero error value or throws an
                exception that encapsulates a non-zero error value on
                failure, and returns 0 on success.
            </span>
        </span>
    </p>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp9344800"></a>Parameters</h3>
            </div>
          </div>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp9345184"></a>request</h4>
              </div>
            </div>
          </div>
          <p>
                 Refers to an array of Dbt handles.  For more
                 information, see
                 <a class="xref" href="dbt.html" title="Chapter 4.  The Dbt Handle">
                The Dbt Handle
        </a>.
             </p>
          <p>
                 Any flags provided to the Dbt handles used in this
                 array are ignored.
             </p>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp9340936"></a>nrequest</h4>
              </div>
            </div>
          </div>
          <p>
                 Indicates how many elements are contained in the
                 <code class="literal">msg</code> array.
             </p>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp9344040"></a>response</h4>
              </div>
            </div>
          </div>
          <p>
                 Points to a single Dbt handle, which is used to
                 receive the response from the remote site. By default, the
                 response is expected to be a single-part message.  If
                 there is a possibility that the response could be a
                 multi-part message, specify <code class="literal">DB_MULTIPLE</code>
                 to this method's <span class="bold"><strong>flags</strong></span>
                 parameter.
             </p>
          <p>
                 The response Dbt should specify one of the
                 following flags:
                 <code class="literal">DB_DBT_MALLOC</code>, <code class="literal">DB_DBT_REALLOC</code>,
                 or <code class="literal">DB_DBT_USERMEM</code>.
             </p>
          <p>
                 For more information on configuring and using
                 Dbts, see 
                 <a class="xref" href="dbt.html" title="Chapter 4.  The Dbt Handle">
                The Dbt Handle
        </a>.
             </p>
          <p>
                 Note that the response Dbt can be empty. In this
                 way an application can send an acknowledgement even if
                 there is no other information that needs to be sent.
             </p>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp9332504"></a>timeout</h4>
              </div>
            </div>
          </div>
          <p>
                 Configures the amount of time that may elapse while this
                 method waits for a response from the remote site. If this
                 timeout period elapses without a response, this method
                 returns with an error condition.
             </p>
          <p>
                  The timeout value must be specified as an unsigned 32-bit
                  number of microseconds, limiting the maximum timeout to
                  roughly 71 minutes.
             </p>
          <p>
                 A timeout value of <code class="literal">0</code>
                 indicates that the channel's default timeout value should
                 be used. This default is configured using the 
                 <a class="xref" href="dbchannel_set_timeout.html" title="DbChannel::set_timeout()">DbChannel::set_timeout()</a>
                 method.
             </p>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp9327720"></a>flags</h4>
              </div>
            </div>
          </div>
          <p>
                  This parameter must be set to either
                  <code class="literal">DB_MULTIPLE</code> or 0.
             </p>
          <p>
                 If there is a possibility that the response can consist of
                 multiple Dbt handles, specify
                 <code class="literal">DB_MULTIPLE</code> to this parameter. In that
                 case, the response buffer is formatted for bulk
                 operations.
             </p>
        </div>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp9348672"></a>Errors</h3>
            </div>
          </div>
        </div>
        <p>
            The <code class="methodname">DbChannel::send_request()</code>
            <span>
            
            <span>
                method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a> 
                exception, encapsulating one of the following non-zero errors, or return one
                of the following non-zero errors:
            </span>
        </span>
         </p>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp9353168"></a>DB_BUFFER_SMALL</h4>
              </div>
            </div>
          </div>
          <p>
                <code class="literal">DB_MULTIPLE</code> was not specified for the
                response Dbt, but the remote site sent a response
                consisting of more than one Dbt; or a buffer
                supplied using <code class="literal">DB_DBT_USERMEM</code>
                was not large enough to contain the message response.
            </p>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp9355624"></a>DB_NOSERVER</h4>
              </div>
            </div>
          </div>
          <p>
                A message was sent to a remote site that has not
                configured a message dispatch call-back function.
                Use the
                <a class="xref" href="repmgr_msg_dispatch.html" title="DbEnv::repmgr_msg_dispatch()">DbEnv::repmgr_msg_dispatch()</a>
                method at every site belonging to the replication group to configure a 
                message dispatch call-back function.
            </p>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp9334448"></a>EINVAL</h4>
              </div>
            </div>
          </div>
          <p>
                If this method is called from a Base API application,
                or if an invalid flag value or parameter was specified.
            </p>
        </div>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp9352088"></a>Class</h3>
            </div>
          </div>
        </div>
        <p>
            <a class="link" href="env.html" title="Chapter 5.  The DbEnv Handle">DbEnv</a>  
        </p>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp9345448"></a>See Also</h3>
            </div>
          </div>
        </div>
        <p>
             <a class="xref" href="rep.html#replist" title="Replication and Related Methods">Replication and Related Methods</a> 
        </p>
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